# https://qiita.com/AkariLuminous/items/3e2c80baa6d5e6f3abe9#4-floor_sum
mod = 10**9 + 7
def floor_sum(n, m, a, b):
    ans = 0
    while True:
        if a >= m or a < 0:
            ans += n * (n - 1) * (a // m) // 2
            ans %= mod
            a %= m
        if b >= m or b < 0:
            ans += n * (b // m)
            ans %= mod
            b %= m
        y_max = a * n + b
        if y_max < m: break
        n, b, m, a = y_max // m, y_max % m, a, m
    return ans   

N = int(input())
M = int(input())
A = list(map(int, input().split()))
B = list(map(int, input().split()))

ans = 0
for a in A:
    for b in B:
        ans += floor_sum(b + 1, b, a, 0) * 2
        ans %= mod
        
print(ans)